Re: [Haskell-cafe] [GHC 7.8.4] IO Monad leak space?

On Fri, Jul 03, 2015 at 08:18:55AM +0000, Baojun Wang wrote:

Consider below function:

f3 :: UArray Int Int -> IOUArray Int Int64 -> Int -> IO () f3 u r i = let !v = u ! i in go (f31 v) i i where f31 v j = readArray r j >>= \v1 -> writeArray r j (v1 + (fromIntegral i) * (fromIntegral v)) f31 :: Int -> Int -> IO () go g k s = when (k <= maxn) ( g k >> go g (s+k) s )

When call f3:

loopM_ (f3 uu res) 1 1 1000000

Could you provide complete working code (including definitions of uu and res) and I will have a go at diagnosing. (My first guess is that you need to force (v1 + (fromIntegral i) * (fromIntegral v)).) Tom